title: Temporal variations of atmospheric aerosol in four European urban areas.
abstract: OBJECTIVE
  The concentrations of PM(10) mass, PM(2.5) mass and particle number were continuously measured for 18 months in urban background locations across Europe to determine the spatial and temporal variability of particulate matter.
  
  
  METHODS
  Daily PM(10) and PM(2.5) samples were continuously collected from October 2002 to April 2004 in background areas in Helsinki, Athens, Amsterdam and Birmingham. Particle mass was determined using analytical microbalances with precision of 1 μg. Pre- and post-reflectance measurements were taken using smoke-stain reflectometers. One-minute measurements of particle number were obtained using condensation particle counters.
  
  
  RESULTS
  The 18-month mean PM(10) and PM(2.5) mass concentrations ranged from 15.4 μg/m(3) in Helsinki to 56.7 μg/m(3) in Athens and from 9.0 μg/m(3) in Helsinki to 25.0 μg/m(3) in Athens, respectively. Particle number concentrations ranged from 10,091 part/cm(3) in Helsinki to 24,180 part/cm(3) in Athens with highest levels being measured in winter. Fine particles accounted for more than 60% of PM(10) with the exception of Athens where PM(2.5) comprised 43% of PM(10). Higher PM mass and number concentrations were measured in winter as compared to summer in all urban areas at a significance level p < 0.05.
  
  
  CONCLUSIONS
  Significant quantitative and qualitative differences for particle mass across the four urban areas in Europe were observed. These were due to strong local and regional characteristics of particulate pollution sources which contribute to the heterogeneity of health responses. In addition, these findings also bear on the ability of different countries to comply with existing directives and the effectiveness of mitigation policies.
authors.affiliation: Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Lianou
authors.forename: Marie-Cecile
authors.initials: MC
authors.lastname: Chalbot
authors.forename: Ilias G
authors.initials: IG
authors.lastname: Kavouras
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kotronarou
authors.forename: Anna
authors.initials: A
authors.lastname: Karakatsani
authors.forename: Antonis
authors.initials: A
authors.lastname: Analytis
authors.forename: Klea
authors.initials: K
authors.lastname: Katsouyanni
authors.forename: Arto
authors.initials: A
authors.lastname: Puustinen
authors.forename: Kaarle
authors.initials: K
authors.lastname: Hameri
authors.forename: Marko
authors.initials: M
authors.lastname: Vallius
authors.forename: Juha
authors.initials: J
authors.lastname: Pekkanen
authors.forename: Claire
authors.initials: C
authors.lastname: Meddings
authors.forename: Roy M
authors.initials: RM
authors.lastname: Harrison
authors.forename: Jon G
authors.initials: JG
authors.lastname: Ayres
authors.forename: Harry
authors.initials: H
authors.lastname: ten Brick
authors.forename: Gerard
authors.initials: G
authors.lastname: Kos
authors.forename: Kees
authors.initials: K
authors.lastname: Meliefste
authors.forename: Jeroen
authors.initials: J
authors.lastname: de Hartog
authors.forename: Gerard
authors.initials: G
authors.lastname: Hoek
mesh_terms: D000336:Aerosols / Q000032:analysis*; D000393:Air Pollutants / Q000032:analysis*; D001272:Atmosphere / Q000737:chemistry*; D002947:Cities; D004784:Environmental Monitoring; D005060:Europe; D006801:Humans; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons; D013997:Time Factors; D001335:Vehicle Emissions / Q000032:analysis
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions